Yes. It is necessary to replace the solar light batteries 1-2 years after, or when you find the lasting time of the solar lights gets much shorter than before, you should consider changing new batteries in the solar light.
The solar lights can be automatically turn off when dawn comes. They have a lighting sensing control system and can auto on/off when sensing darkness/brightness.
Yes, you can. You can use a suitable power charger adaptor to charge the solar lights if needed. The solar lights can be charged like a cellphone if you get the right charger. (only when you have to make the solar lights on and you find no way to get sunlight for days)
Yes, the solar lights can be charged on cloudy days but probably not fully charged in a day, it can still use the stored energy from the batteries and light on at night.
Normally, the batteries in solar lights can last about 2-3 years before replacement needed. LEDs, the solar panels can last 10 years or more.
Most of the solar lights can be automatically turn on at night, cos when the solar panel detects it’s dark, the control system can make the LED light turned on.
It depends on how the solar lights manufacturers set while producing them. Normally the solar lights can last more than 8 hours at night if they get full charge during the daytime (at least 6 hours getting sunlight). Judn offers 10 hours lasting time, some project customed solar lights can last 12 hours.
Yes, all Judn solar lights are designed to stay on an entire night, on the condition that the batteries are fully charged during the daytime. If after some rainy days, the battery's power is not enough, then probably they can’t last all night.